Robust manual control of a manufacturing system using supervisory control theory
Paper in proceedings, 2014
There are many situations where manual intervention in automated systems, such as flexible manufacturing systems, is inevitable. Commonly the control of a manufacturing system is implemented in terms of operations, and sequences thereof, and these operations can typically be run manually. However, running the operations in arbitrary order may lead to situations such as blocking or collisions, from which it its hard or even impossible to recover or to resume automatic execution. This paper describes an implementation of an operator interface for robust manual control of a manufacturing system, where the operator is aided not to manually drive the system into a state that breaches the system requirements. Hence, blocking and collisions are avoided, and automatic mode can always be resumed. From a model of the manufacturing system based on self-contained operations, each of which is identified in terms of events with preconditions, a supervisor is calculated by use of the Supervisory Control Theory framework. From this supervisor additional preconditions are extracted for each operation. The operations with the extended preconditions are then ported to an operator interface which allows manual control of the production cell by dynamically guiding the operator to only those operations for which the extended preconditions are satisfied.
Extended finite state machines
Supervisory control theory